It is proposed to study: (1) properties of adrenodoxin-adrenodoxin reductase complex, (2) purification and properties of cytochrome P450scc and cytochrome P45011 beta, (3) cholesterol availability for steroid hydroxylase complex. The method of procedures used in this proposal are mainly extensive purification and characterization of enzymes and proteins. By means of reconstitution of these components into a system close to that in the native system of adrenal cortex mitochondria, we hope to understand the relationship between the steroidogenesis and the action of ACTH in adrenal cortex.